Can type secondary battery and method of manufacturing circuit board for the secondary battery

Abstract

A can type secondary battery and a method of manufacturing a circuit board for the secondary battery that improves reliability by providing a consistent breakdown pressure of the circuit board used in the can type secondary battery. The can type secondary battery includes an electrode assembly, a can to house the electrode assembly and a cap assembly combined with the can. The cap assembly includes a circuit board, which includes fiber layers and is broken by a safety vent when an internal pressure of the can is increased. A woven direction of the fiber layers is inclined with respect to a length direction of the circuit board. Distribution of the breakdown pressure among the circuit boards is decreased, and thus the circuit boards are broken under a consistent pressure, thereby improving the reliability of the can type secondary battery.

1. A can type secondary battery, comprising:
 an electrode assembly; 
 a can housing the electrode assembly, the can having an opening at one end thereof; and 
 a cap assembly in the opening of the can, the cap assembly comprising:
 a cap up electrically connected to the electrode assembly, 
 a circuit board between the cap up and the electrode assembly, the circuit board comprising a plurality of woven fiber layers, each of the woven fiber layers having a woven direction which is inclined with respect to a length direction of the circuit board, resin layers formed between, on a first side of, and on a second side of the plurality of woven fiber layers, wherein the resin layer between the woven fiber layers is thicker than the resin layers on the first side and on the second side of the woven fiber layers; and a circuit pattern on one of the resin layers, wherein the circuit board is configured to be fractured by a safety vent; 
 a safety vent between the circuit board and the electrode assembly, the safety vent being deformable by an internal pressure of the secondary battery to break the circuit board, and 
 an insulation gasket to insulate the cap up, the circuit board, and the safety vent from the can. 
 
 
     
     
       2. The can type secondary battery of  claim 1 , wherein the circuit board comprises:
 an edge part having an annular shape; and 
 a breakdown part formed to cross a central portion of the edge part, 
 wherein the woven fiber layer is inclined with respect to a length direction of the breakdown part. 
 
     
     
       3. The can type secondary battery of  claim 2 , wherein the breakdown part comprises breakdown grooves formed at positions facing each other in a direction perpendicular to the length direction of the breakdown part. 
     
     
       4. The can type secondary battery of  claim 3 , wherein the breakdown grooves are formed about a central portion of the breakdown part. 
     
     
       5. The can type secondary battery of  claim 2 , wherein a bending groove is formed where the edge part and the breakdown part connect. 
     
     
       6. The can type secondary battery of  claim 2 , wherein the breakdown part comprises a hole formed in a central portion of the breakdown part. 
     
     
       7. The can type secondary battery of  claim 2 , wherein the breakdown part comprises holes formed at positions facing each other about a central portion of the breakdown part in the length direction of the breakdown part. 
     
     
       8. The can type secondary battery of  claim 1 , wherein the woven fiber layer comprises:
 woven glass fiber and/or a woven polyimide fiber layers bound together by resin layers formed between the woven glass and/or polyimide fiber layers. 
 
     
     
       9. The can type secondary battery of  claim 1 , wherein the woven direction is inclined with respect to a length direction of the circuit board at about 45°. 
     
     
       10. The can type secondary battery of  claim 1 , wherein the woven direction is one of a warp and a weft of the fiber layer. 
     
     
       11. A can type secondary battery, comprising:
 an electrode assembly; 
 a can housing the electrode assembly, the can having an opening at one end thereof; and
 a cap assembly in the opening of the can, the cap assembly comprising: 
 a cap up electrically connected to the electrode assembly, a circuit board between the cap up and the electrode assembly, the circuit board including a plurality of woven fiber layers, a resin layer formed between, on a first side of, and on a second side of the fiber layers; and a circuit pattern on one of the resin layers, wherein the resin layer between the woven fiber layers is thicker than the resin layers on the first side and on the second side of the woven fiber layers; wherein adjacent ones of the woven fiber layers face each other, and wherein the circuit board is configured to be fractured by a safety vent; 
 a safety vent located between the circuit board and the electrode assembly and configured to break the circuit board, and 
 an insulation gasket to insulate the cap up, the circuit board, and the safety vent from the can. 
 
 
     
     
       12. The can type secondary battery of  claim 11 , wherein the woven fiber layer comprises woven glass fiber and/or woven polyimide fiber layers bound together by the resin layers formed therebetween. 
     
     
       13. The can type secondary battery of  claim 11 , wherein the circuit board comprises:
 an edge part having an annular shape; and 
 a breakdown part formed to cross a central portion of the edge part, 
 wherein the woven fiber layers are inclined with respect to a length direction of the breakdown part. 
 
     
     
       14. The can type secondary battery of  claim 13 , wherein the breakdown part comprises breakdown grooves formed at positions facing each other in a direction perpendicular to the length direction of the breakdown part. 
     
     
       15. The can type battery of  claim 14 , wherein the breakdown grooves are formed about a central portion of the breakdown part. 
     
     
       16. The can type secondary battery of  claim 13 , wherein a bending groove is formed at a part where the edge part and the breakdown part connect. 
     
     
       17. The can type secondary battery of  claim 13 , wherein the breakdown part comprises a hole formed in a central portion of the breakdown part. 
     
     
       18. The can type secondary battery of  claim 13 , wherein the breakdown part comprises holes formed at positions facing each other about a central portion of the breakdown part in the length direction of the breakdown part.